Real facts about the Muslim population in Europe.

Recent killings in Paris as well as the arrival of hundreds of thousands of mostly Muslim refugees in Europe have drawn renewed attention to the continent’s Muslim population. In many European countries, including France, Belgium, Germany, the United Kingdom and the Netherlands, concerns about growing Muslim communities have led to calls for restrictions on immigration. But just how large is Europe’s Muslim population, and how fast is it growing?

Using the Pew Research Center’s most recent population estimates, here are five facts about the size and makeup of the Muslim population in Europe:

1. Germany and France have the largest Muslim populations among European Union member countries. As of 2010, there were 4.8 million Muslims in Germany (5.8% of the country’s population) and 4.7 million Muslims in France (7.5%). In Europe overall, however, Russia’s population of 14 million Muslims (10%) is the largest on the continent.

2. The Muslim share of Europe’s total population has been increasing steadily. In recent decades, the Muslim share of the population throughout Europe grew about 1 percentage point a decade, from 4% in 1990 to 6% in 2010. This pattern is expected to continue through 2030, when Muslims are projected to make up 8% of Europe’s population.

3. Muslims are younger than other Europeans. In 2010, the median age of Muslims throughout Europe was 32, eight years younger than the median for all Europeans (40). By contrast, the median age of religiously unaffiliated people in Europe, including atheists, agnostics and those with no religion in particular, was 37. The median age of European Christians was 42.

4. Views of Muslims vary widely among European countries. A Pew Research Center survey conducted this spring found that majorities in France, Britain and Germany had favorable views of Muslims. Opinion was on balance favorable in Spain while negative views prevailed in Italy and Poland. Views about Muslims are tied to ideology. While 36% of Germans on the political right give Muslims an unfavorable rating, just 15% on the left do so. The gap between left and right is also roughly 20 percentage points in France and Italy. And significant differences are found in the UK as well.

5. As of 2010, the European Union was home to about 13 million Muslim immigrants. The foreign-born Muslim population in Germany is primarily made up of Turkish immigrants, but also includes many born in Kosovo, Iraq, Bosnia-Herzegovina and Morocco. The roughly 3 million foreign-born Muslims in France are largely from France’s former colonies of Algeria, Morocco and Tunisia.

CORRECTION: An earlier version of this post cited a 2014 Ipsos MORI poll on peoples’ perceptions about the size of the Muslim population in European countries. The reference was deleted because the poll was conducted through an online panel for which the participants are recruited in a way that does not allow us to know each respondent’s chance of being selected.